.d div{
    width: 50px;
    height: 50px;
    border-radius: 50%;
    border: 2px solid rgb(151, 137, 137);
}
.d span{
    display: block;
    text-align: center;
    line-height: 50px;
    color: white;
}
.d div:nth-child(2n){
    background-color: red;
}
.d div:nth-child(2n-1){
    background-color: blue;
}
.d div{
    float: left;
}
body{
    background-image: url(../img/背景2.jpg);
    background-repeat: no-repeat;
}
.d{
    width: 600px;
    height: 600px;
    position: absolute;
    top: 50%;
    right: 28%;
}